JPH089670B2 - Polyester film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a biaxially oriented polyester film.

[Prior Art] As a biaxially oriented polyester film, a film made of polyester containing inert inorganic particles is known (for example, JP-A-59-178224).

[Problems to be Solved by the Invention] However, the above-mentioned conventional biaxially oriented polyester film has a process speed of a film processing step, for example, a printing step in a packaging application, a magnetic layer application in a magnetic medium application, and a calendar step. As the surface of the film is scraped with a roll that comes into contact with the increase,
Recently, the drawback of product performance has become a problem.

The present invention solves these problems and improves the surface "scratch resistance".
It is intended to provide an excellent film of.

[Means for Solving Problems] A biaxially oriented film containing a polyester and a composition comprising at least one kind of inert inorganic particles as a main component, wherein Raman by a carbonyl group of the polar surface layer of at least one surface of the film is used. The biaxially oriented polyester film is characterized in that the full width at half maximum of the band is 1 cm ^-1 or more larger than the full width at half maximum inside the film.

The polyester in the present invention means ethylene terephthalate, ethylene α, β-bis (2-chlorophenoxy) ethane-4,4′-dicarboxylate, ethylene 2,6
-At least one structural unit selected from naphthalate units is the main constituent. However, other components may be copolymerized within a range not hindering the present invention, preferably within 5 mol%.

Further, in the case of polyester having ethylene terephthalate as a main constituent component, abrasion resistance is further improved, which is particularly desirable.

The type of the inert inorganic particles in the present invention is not particularly limited, but when the crystallization acceleration coefficient is in the range of -5 to 20 ° C, preferably -5 to 15 ° C, more preferably 0 to 10 ° C, The Raman band full width at half maximum in the range of the invention is very easily obtained, which is particularly desirable. Furthermore, among them, substantially spherical silica derived from colloidal silica, synthetic calcium carbonate, titanium oxide, and α-alumina are particularly desirable. The colloidal silica referred to here is preferably particles produced from sodium silicate as a raw material in the process of removing alkali components.

The content of the inert inorganic particles in the present invention is not particularly limited, but is preferably 0.05 to 1.0% by weight, particularly 0.1 to 0.8% by weight because the abrasion resistance is further improved.

The average particle size of the inert inorganic particles in the present invention is not particularly limited, but is preferably 0.1 to 1.0 μm, particularly 0.15 to 0.8 μm because the abrasion resistance is further improved.

The inert inorganic particles in the present invention may be two or more kinds, or two or more kinds of the same kind having different average particle diameters may be used in combination or may be used in combination with the internally precipitated particles. The film of the present invention contains the above-mentioned composition as a main component, but may be blended with other polymers within a range that does not impair the object of the present invention, and may further contain an antioxidant, a heat stabilizer, a lubricant, and an ultraviolet absorbing agent. Inorganic or organic additives such as agents and nucleating agents may be added to the extent that they are usually added.

The film of the present invention is a film in which the above composition is biaxially oriented. An unstretched film or a uniaxially oriented film is not preferable because it has poor abrasion resistance.

Further, the plane orientation index showing the degree of the biaxial orientation is not particularly limited, but it is particularly desirable in the range of 0.935 to 0.975, particularly 0.940 to 0.970 because the abrasion resistance is further improved.

The half width of the Raman band based on the stretching vibration of the carbonyl group of the film electrode surface layer of the film of the present invention is 1 cm ^-1 than the half width of the Raman band based on the stretching vibration of the carbonyl group inside the film, preferably 2 cm ^-1. More than that is necessary. If the difference between these half widths is smaller than the above range, the abrasion resistance of the film becomes poor, which is not preferable. The upper limit of this difference is not particularly limited, but is usually 8c.
The manufacturing limit is about m ^-1 . Here, the above-mentioned full width at half maximum is to be measured by the method described below, but the full width at half maximum of the Raman band based on stretching vibration of the carbonyl group is inversely related to the density of the polyester, reported by AJ Melveger. (J. Polymer Science
10 , 317,1972).

Further, the full width at half maximum of the Raman band of the carbonyl group of the extreme surface layer of the film of the present invention is not particularly limited, 15 cm ^-1 or more,
When it is preferably 17 cm ^-1 or more, the abrasion resistance is further improved, which is particularly desirable.

The film of the present invention has a surface average roughness Ra in the width direction of 0.005.
˜0.030 μm, particularly 0.007 to 0.020 μm, it is particularly desirable because the abrasion resistance is further improved.

The film of the present invention has a melt viscosity of 100 at 290 ° C. and 200 sec ^−1.
A range of 0 to 10000 poises, particularly 2000 to 7000 poises, is particularly desirable because the abrasion resistance is further improved.

 Next, a method for producing the film of the present invention will be described.

First, as a method of incorporating inert inorganic particles into a predetermined polyester, it may be added during polymerization before polymerization or after polymerization, but it is mixed with ethylene glycol, which is a diol component of polyester, in the form of a slurry, The method of adding after dispersion is effective for satisfying the relational expression of the present invention. Further, as a method of adjusting the content of the inert inorganic particles, a method of diluting a high-concentration master pellet during film formation is effective in obtaining the Raman band half width within the range of the present invention. In this case, by using inert inorganic particles having a Mohs hardness of 3 or more, 195 ° C at the time of ethylene glycol dispersion.
Heat treatment for 2 hours, or 0.5 for inorganic particles
The method of adding about 20% by weight of ammonium phosphate salt is extremely effective in controlling the relationship between the half-width of Raman band in the surface layer of the film and the inner half of the Raman band.

Thus, after sufficiently drying the pellets containing a predetermined amount of inert inorganic particles, it is supplied to a known melt extruder, 27
It is extruded into a sheet from a slit die at 0 to 330 ° C., and cooled and solidified on a casting roll to prepare an unstretched film. In this case, the draft ratio at the time of extrusion (die slit gap / unstretched film thickness) is 5 to 30, preferably 8
It is effective to set the range of -20 to satisfy the Raman band half width of the present invention.

Next, this unstretched film is biaxially stretched and biaxially oriented. As a stretching method, a sequential biaxial stretching method or a simultaneous biaxial stretching method can be used.

In the case of the sequential biaxial stretching method, it is general to stretch in the longitudinal direction and then in the width direction, but the stretching may be performed in the reverse order. The conditions for biaxial stretching are not necessarily constant depending on the stretching method, the type of polymer, etc., but are usually 80 to 160 ° C in both the longitudinal and width directions, preferably 90 to 150 ° C, and the stretching ratio is 3.0 to 5.0, respectively. A range of 2 times, preferably 3.2 to 4.5 times is suitable. The stretching speed is 1 × 10 ^{3 to} 7 × 10 ^4.
% / Min is preferred.

Here, the unstretched film is stretched to 100 to 170 ° C. before stretching.
Then, the heat treatment for 0.1 to 60 seconds is effective for satisfying the Raman band half width of the present invention.

Next, this stretched film is heat treated. The heat treatment conditions at this time are 130 to 210 in an atmosphere such as steam.
The heat treatment in the temperature range of 130 ° C., particularly in the range of 130 to 180 ° C., or the heat treatment by microwaves is extremely effective for satisfying the Raman bandwidth of the present invention. Time is 0.5-60 seconds,
Processing under a fixed length is preferable.

[Operation] In the present invention, the relationship between the Raman band half-value width of the film pole surface layer and the half-value width inside the film detected by a special method, that is, the relation between the density of the film pole surface layer and the density inside the film is set within a specific range. Therefore, it is presumed that the effect of the present invention was obtained as a result of being able to obtain a film having a large impact absorption force when an external shearing force is applied to the film surface.

[Physical property measuring method and effect evaluating method] The characteristic value measuring method and effect evaluating method of the present invention are as follows.

(1) Average particle size of inorganic fine particles Polyester was removed from the film by a plasma ashing method or an o-chlorophenol dissolution method, and this was dispersed in ethanol, followed by centrifugal sedimentation (Horiba, CAPA500).
It is the volume average diameter measured in (use).

(2) Content of inorganic fine particles After adding o-chlorophenol 1.0 to 100 g of polyester and heating at 120 ° C. for 3 hours, ultracentrifuge 55P-72 manufactured by Hitachi Koki Co., Ltd. was used to stretch and separate for 40 minutes at 30,000 rpm. Then, the obtained particles are vacuum dried at 100 ° C. When the melting peak corresponding to the polymer is observed when the fine particles are measured by a scanning differential calorimeter, o-chlorophenol is heated and cooled on the fine particles, and then the stretching separation operation is performed again. When no melting peak is observed, the fine particles are regarded as precipitated particles.
Usually, two stretching separation operations are sufficient.

(3) Full width half maximum Raman band of film outermost layer Ramanor U-1000 Raman system manufactured by Jobin-Yvon was used to measure the total reflection Raman spectrum, and the half width at 1730 cm ^-1 which is the stretching vibration of the carbonyl group was determined. The measurement conditions are as follows. The measurement depth is 500 to 1000Å from the surface.

Light source Argon ion laser (5145Å) Setting the sample Press the film surface to the total reflection prism so that the laser deflection direction (S deflection) and the film longitudinal direction are parallel, and the incident angle of the laser to the prism (with the film thickness direction Angle) was set to 60 °.

Detector PM: RCA31034 / Proton Counting System (Hamamatsu c1230) (SUPPLY 1600V) Measuring condition SLIT 1000μm LASER 100mW GATE TIME 1.0sec SCAN SPEED 12cm ^-1 / min SAMPLING INTERVAL 0.2cm ^-1 REPEAT TIME 6 (4) Inside film ( (Bulk) Raman band half width The same Raman system as in (3) above was used. However,
Without using a total reflection prism, the laser incident angle is 70
By setting the angle to be °, the specularly reflected light escaped, and only the Raman scattered light was detected. That is, in the measurement of the above (3), the information on the extreme surface layer is obtained by utilizing the fact that the light slightly penetrates into the film surface when the light is totally reflected, whereas the Raman inside the film is obtained without total reflection here. The information is obtained from the scattered light. Other conditions are REPEAT / TI
Same as (3) above except that ME is 4 times.

(5) Plane orientation index Using an Abebe refractometer with sodium D line (wavelength 589 nm) as a light source, the biaxially oriented film has a refractive index (A) in the thickness direction and is rapidly cooled into water at 10 ° C. after melt pressing. The refractive index (denoted as B) in the thickness direction of the non-oriented (amorphous) film thus prepared was measured, and A / B was taken as the plane orientation index. Use methylene iodide as the mounting solution at 25 ° C and 65
It was measured at% RH.

(6) Melt viscosity The melt viscosity was measured using a high flow tester at a temperature of 290 ° C. and a shear rate of 200 sec ⁻¹ .

(7) Surface average roughness Ra was measured according to JIS-B-0601 using a stylus type surface roughness meter. However, the cutoff is 0.08 mm, and the measurement length is 1 m.
It was m.

(8) Glass transition point Tg, cold crystallization temperature Tcc It was measured using a Perkin-Elmer DSC (differential scanning calorimeter) type II. The DSC measurement conditions are as follows.
That is, 10 mg of a sample is set in a DSC apparatus, melted at a temperature of 300 ° C. for 5 minutes, and then rapidly cooled in liquid nitrogen. The temperature of this quenched sample is raised at 10 ° C./min, and the glass transition point Tg is detected.
The temperature was further raised, and the crystallization exothermic peak temperature from the glass state was set as the cold crystallization temperature Tcc. Here, the difference between Tcc and Tg (Tcc-Tg) is defined as ΔTcg.

(9) Crystallization acceleration coefficient (unit: ° C.) ΔTcg (I) of the polyester containing 1% by weight of the inert inorganic particles by the above method, and ΔTcg (I) of the polyester containing no inert inorganic particles of the same viscosity. Tcg (II) is measured and the difference between ΔTcg (II) and ΔTcg (I) [ΔTcg (II)-
ΔTcg (I)] was used as the crystallization promoting coefficient of the inert inorganic particles.

(10) Scraping resistance A film is slit into a tape with a width of 1/2 inch, a single blade is pressed vertically, and the product is run for 20 cm while being pushed 0.5 mm (running tension 500 g, running speed 6.7 cm /
Seconds). At this time, the height of the shavings on the surface of the film attached to the tip of the single blade was read with a microscope and used as the shaving amount (unit: μ
m). When the abrasion amount (average value on both surfaces) was 15 μm or less, abrasion resistance was good, and when it was more than 15 μm, abrasion resistance was judged to be poor. The scraped amount: 15 μm is a critical point whether or not a process surface or product performance trouble occurs due to scraping of the film surface in a processing step such as a printing step or a calendar step.

[Examples] The present invention will be described based on Examples.

Example 1 Titanium oxide having an average particle size of 0.3 μm was dispersed in ethylene glycol in a slurry form at a concentration of 1% by weight. This time,
To titanium oxide, 1% by weight of tetraethylammonium phosphate (phosphoric acid and tetraethylammonium hydroxide were mixed at a molar ratio of 1: 1) was added, and glass beads having a diameter of 50 μm were dispersed as a medium. Was removed to prepare a slurry. This ethylene glycol and dimethyl terephthalate were transesterified and then polycondensed to produce polyethylene terephthalate containing 1% by weight of titanium oxide particles. The crystallization acceleration coefficient of this titanium oxide was 2.5 ° C.

The polyethylene terephthalate pellets and the polyethylene terephthalate pellets containing no inorganic particles were mixed so that the titanium oxide content was 0.4% by weight. This mixed pellet was dried under reduced pressure at 180 ° C for 3 hours (3To
rr) did. These pellets are supplied to an extruder, melt-extruded at 300 ° C, the draft ratio is set to 15, and the surface temperature is wrapped around a casting drum at a surface temperature of 30 ° C by using the electrostatically applied casting method to cool and solidify, and the thickness is about 180 μm. Of unstretched film. This unstretched film was heat-treated at 130 ° C. for 1 minute and then stretched at 90 ° C. in the longitudinal direction by a factor of 3.4.

This drawing was carried out at a peripheral speed difference between the two sets of rolls, and the drawing speed was 10,000% / min. This uniaxial film was stretched 3.6 times in the axial direction at 100 ° C. at a stretching rate of 2000% / min using a stenter. This film was heat-treated in steam at 140 ° C. for 20 seconds to obtain a biaxially oriented film having a thickness of 15 μm. The Raman band half width of the extreme surface layer of this film is 18c on both sides.
m ^-1 , the Raman band half width at the inside of the film is 16 cm ^-1 ,
The difference was 2 cm ^-1 , which satisfied the relationship of the present invention. As a result of examining the abrasion resistance of the surface of this film, the abrasion amount was 4 μm and the abrasion resistance was good.

Examples 2 to 4 and Comparative Examples 1 to 3 Various inorganic particles having an average particle diameter of 0.5 μm were dispersed in ethylene glycol in the form of a slurry by changing the dispersion method (the concentration of the inorganic particles was 1% by weight). This ethylene glycol and dimethyl terephthalate were transesterified and then polycondensed to produce polyethylene terephthalate containing 1% by weight of inorganic particles. The crystallization acceleration coefficient of these inorganic particles was as shown in Table 1.

These polyethylene terephthalate pellets and polyethylene terephthalate pellets containing no inorganic particles were mixed so that the content of inorganic particles was 0.25% by weight. This mixed pellet was dried under reduced pressure at 180 ° C for 3 hours (3 Tor
r) done. These pellets were fed to an extruder, melt-extruded at 300 ° C, and the draft ratio was set to 15. The pellet was wound around a casting drum with a surface temperature of 30 ° C using an electrostatic cast method to be cooled and solidified to a thickness of about 180 μm. An unstretched film was made. After various processing of this unstretched film, 90 ℃
Was stretched 3.4 times in the longitudinal direction.

This drawing was carried out at a peripheral speed difference between the two sets of rolls, and the drawing speed was 10,000% / min. This uniaxial film was stretched 3.6 times in the width direction at 100 ° C. at a stretching rate of 2000% / min using a stenter. This film was heat-treated for 10 seconds by various methods to obtain a film having a thickness of 15 μm.

The Raman band full width at half maximum of these films, the Raman band half width at the inside of the film, and the abrasion resistance of the film are as shown in Table 1. When the Raman band half width is within the range of the present invention Had good abrasion resistance, but otherwise it was poor. It can be seen that even if the types of the inert inorganic particles are the same, the abrasion resistance greatly differs depending on the Raman band half-value width relationship of the film.

EFFECTS OF THE INVENTION The present invention controls the relationship between the Raman band half-value width of the film polar surface layer and the half-value width inside the film, that is, the relationship between the density of the film polar surface layer and the internal density, which is detected by a special method. As a result, the abrasion resistance of the surface can be improved, and even if the processing speed is increased, it is possible to obtain a film in which the surface of the film is not scraped, which causes troubles in the product performance in the processing process. It is a thing.

The use of the film of the present invention is not particularly limited, but the film of the present invention is useful as a base film for a magnetic recording medium, particularly a video tape, in which abrasion of the film tends to cause troubles in product performance.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display area C08L 67:02

Claims (1)

[Claims] 1. A biaxially oriented film comprising a polyester and a composition comprising at least one kind of inert inorganic particles as a main component, wherein the film has at least one extreme surface layer (a depth from the surface of the film of up to 1000 Å). The biaxially oriented polyester film is characterized in that the half-value width of the Raman band due to the carbonyl group of (part) is larger than the half-value width inside the film (the part other than the film outermost layer) by 1 cm ^-1 or more.